I've been working on this project where I want to calculate the passed time during a state. I need to do it using the function millis().
When I write the code with delays, everything works well. However when I add my if parameters, I can't get what I want.
As you will see in the picture where I compare the two codes, I want to start counting once my pin reads HIGH and store that value (with "ilk") until the pin reads a LOW ("son") and store that too. Then subtract the two stored values from each other to give me the time that passed between a LOW and a HIGH state.
The problem is, as the millis keeps running, the value for "ilk" will always follow it. What I want to do is to keep the first value of the millis when its on a HIGH state and store it and don't change it UNTIL I get a LOW state. Then when the HIGH state repeats it shall change.
I hope I could make things clear.
Thanks in advance.
/CODE WITHOUT IF PARAMETERS/
int ilk,son,fark;
void setup() {
Serial.begin(9600);
}
void loop() {
ilk = millis();
Serial.print("ilk:");
Serial.println(ilk);
delay(1000);
son = millis();
Serial.print("son:");
Serial.println(son);
fark = son - ilk;
Serial.print("fark:");
Serial.println(fark);
Serial.print("\n");
}
/CODE WITH THE IF PARAMETERS/
int pin=9;
int state, last_state;
int ilk,son,fark;
void setup() {
Serial.begin(9600);
pinMode(pin, INPUT_PULLUP);
}
void loop() {
state=digitalRead(pin);
if(state==HIGH){
ilk = millis();
Serial.println("on");
}
if(state!=last_state){
if(state==LOW){
son = millis();
Serial.println("\noff");
Serial.print("ilk:");
Serial.println(ilk);
Serial.print("son:");
Serial.println(son);
}
last_state=state;
}
}
From looking at your program I'm not sure what you want to happen. The usual way to use millis() to time something is to save the value when the action starts and then check for when the time interval has elapsed - something like this
if (millis() - actioStartTime >= interval) {
// time is up
// do something
}
NOTE that all variables used with millis() must be defined as unsigned long - and not int as you have done
Have a look at how millis() is used to manage timing without blocking in Several Things at a Time.
The problem is, as the millis keeps running, the value for "ilk" will always follow it. What I want to do is to keep the first value of the millis when its on a HIGH state and store it and don't change it UNTIL I get a LOW state
Compare the state of the pin with what it was the previous time you read it. If it has changed then determine whether it is now HIGH or LOW. If it is now HIGH, save the value of millis(). If it is now LOW then the timing period is over. Save the value of millis() now and do whatever you need with the start and end values.
You seem to be trying to do this in your code but need to save the value of millis() only when the state has changed, not every time through loop()
This has been a useful thread for me, as I'm just learning how to apply similar 'millis/state combinations'. I was getting close after an hour or so, before seeing your successful code, thanks.
I made some changes:
from your (Turkish?) variable names so that I could better follow it:
used <Ctrl + t> to autoformat it
increased baud rate to 115200 instead of 9600
Used pin 6 instead of 9
One minor query: I'm using a mini-button on my breadboard to deliver the low inputs to pin 6 and I'm puzzled why the serial output always shows the first line of the output when I release the button. I expected to see all three lines as soon as I pressed the button?
unsigned long first, last, difference;
int pin = 6, read, last_read; // Changed from pin 9
void setup()
{
Serial.begin(115200);
pinMode(pin, INPUT_PULLUP);
}
void loop()
{
read = digitalRead(pin);
if (read != last_read)
{
if (read == HIGH)
{
first = millis();
Serial.print("first:");
Serial.println(first);
}
else if (read == LOW)
{
last = millis();
Serial.print("last:");
Serial.println(last);
difference = last - first;
Serial.print("difference (ms):");
Serial.println(difference);
Serial.println("*************");
}
last_read = read;
}
}
You can change what Auto format does, such as removing blank lines in functions, putting spaces around operators, adding a space after if/for and while and moving braces onto their own lines, all of which I find particularly useful after copying code from the forum and in tidying up my own sketches
Find the folder in which preferences.txt is stored. If you don't know where preferences.txt is stored, open the IDE, File -> Preferences and you'll find a link
Copy the attached file into that folder. If you look at the file with an editor (which you should) you will see a link to http://astyle.sourceforge.net/astyle.html giving details of the formatting commands
The attached file is how I have got my IDE set up, but you can, of course, change it to suit your requirements
Thanks, neat. I'd modified formatter.conf soon after installing the IDE, primarily to get all opening curly brackets on a new line. But yours is nicer, especially the deletion of empty lines. Mind you, I may regret that as I do like lots of space around key lines while I'm learning ...
The value for "fark" is absurd (4294965223~)